I. Field of the Invention
This invention relates to a polyester film with good adhesion.
II. Description of Related Art
Polyester films are widely used as, for example, as wrapping material, base film for photosensitive materials, base film for magnetic recording materials, printing materials, and so on in a wide variety of fields. In these uses, the polyester films are often adhered to other materials such as photosensitive materials, magnetic recording materials, inks and other films, etc. In these cases it is preferred that the polyester film have good adhesion or receptive properties for the material to which the film is adhered.
Conventional techniques for creating good adhesion for a polyester film include surface activation methods (e.g., U.S. Pat. Nos. 3,018,189, 4,072,769 and 3,364,056) in which the surface of the polyester film is activated by corona discharge treatment, ultraviolet irradiation treatment, plasma treatment, flame treatment or the like; surface etching methods (e.g., U.S. Pat. No. 3,186,883) in which the surface of the polyester film is treated with a chemical such as an acid, alkali, aqueous amine solution, trichloroacetate or the like; and methods (e.g., U.S. Pat. Nos. 4,224,270 and 3,136,655) in which a primer layer made of a polyester, acrylic resin, polyurethane or the like is formed on the surface of the polyester film.
However, most of the above-mentioned conventional methods cannot give the polyester film sufficient adhesion. Further, even in cases where the polyester film exhibits good adhesion to a material having similar chemical structure to the polyester, if the composite film comprising the polyester film and is immersed in aqueous ammonia solution or in boiling water, the material is often peeled off from the polyester film or the polyester film often hazes.